The invention relates to a holder for the attachment of diagnostic and therapeutic devices to the skin at a certain predetermined site of the human body.
Diagnostic and therapeutic devices intended to be attached to the human body for a longer period than a few seconds are normally kept in place by adhesive tape, by fixation with rubber bands or in a similar way. For ECG-electrodes, fixation arrangements of an essentially different kind have been described where fixation is achieved with the aid of vacuum.
Said known arrangements for fixation display various drawbacks. The method of attachment by adhesive tape is simple but does not provide for the easy displacement of the device to another site of the skin, in case it had not been put in the right place from the beginning. Moreover, adhesive tape may cause inconvenience when removed from areas with hair growth, may fall off through the effect of transpiration, or may, in the case of uncautious handling during application, fasten in places not considered for application. With said fixation arrangements, it is moreover not easy to bring into skin contact diagnostic and therapeutic devices in a way that guarantees a constant force over time to be exerted by the device onto the skin. Keeping the force of attachment constant is important in, e.g., receiving electrical or acoustic signals through the skin.
An ECG-electrode integrated arrangement for attachment displaying the characteristics of the preamble of claim 1, which is thus considered to be fastened by vacuum provided through a tube, and which has a valve in closed position when the electrode is not being attached opening automatically when it is applied, and closing automatically when the electrode falls off, is known by the Austrian patent specification No. 248608.
According to an embodiment described there, a spring-biassed electrode plate with the aid of an elastic diaphragm is coupled to a surrounding sealing ring. When the electrode plate is pressed against the skin of a patient, a valve opens and vacuum is applied to a cavity extending around the electrode, delimited by the sealing ring.
Unfortunately, it has been found that the electrode plate abuting against the skin becomes swiveling and axially movable in relation to the sealing ring, resulting in inferior skin attachment and in a varying contact between the skin and the electrode when there is movement.
A holder integrated with an ECG-electrode, which is held in position by means of vacuum and which has a surrounding sealing ring which is relatively rigidly connected to a centrally located electrode plate, is known from the U.S. Pat. No. 4,248,243. With this electrode, however, suction cannot be applied through a tube from a central vacuum source, since it lacks the self-closing valve of the Austrian patent, which valve cannot be combined with the rigid design. In addition to that, the arrangement described in the US patent specification is highly disturbing since it emits a whizzing noise arising in the ejector suction element.